The invention relates to the manufacture and repair of turbine engine components. More particularly, the invention relates to the identification marking of turbine engine elements.
Identification marking of turbine engine components has drawn much recent attention. Although the purposes and uses of such marking may vary, key examples are seen during engine manufacture, repair and, more particularly, engine component repair. It has become standard practice for some manufacturers and repair/refurbishing operations to mark each component as it is received for repair or refurbishing. The markings may be identification markings (e.g., operator-readable alphanumeric serial markings or machine-readable codes (e.g., 2-d dot matrix codes)). The markings may, themselves, contain further information (e.g., date/time of repair, place of repair, repair kind code, or the like) or such information may be stored in a database accessible based upon the markings.
An exemplary marking technique is dot peen indentation marking. Other techniques include laser and/or chemical etching. Dot peen marking has advantages of speed, low cost, and an extreme degree of robustness.
Typical components have a limited portion of surface area suitable for marking. For example, the airfoils of turbine and compressor blades may be off-limits as may other surfaces exposed to the gas path or to high stresses. For such blades, marking at particular locations along the blade platform underside and/or the ends of the blade attachment root may be appropriate. Thus, for a given component, a manufacturer may specify a finite number of accepted marking locations/sites.
With typical marking apparatus, the marking location on the component must have a predetermined spatial relationship to a marking head (i.e., the location must be in an operative marking position). Custom fixtures may be used to hold the components. For example, due to different airfoil and other shapes, different fixtures may be required to hold airfoils of each blade stage in the engine. Staying with the example of blades, the fixtures may have surfaces complementary to the particular shape of the airfoils of the associated stage. A given fixture positions a given one of the permitted locations in the operative marking position. To address the various permitted locations, multiple fixtures may be required for the given component, which is expensive and accommodates valuable work cell space.
Thus, to mark the components as they come in or go out, an operator must inspect each component to see which permitted location(s) have not already been marked. The operator then selects the appropriate unmarked location and selects the fixture or adapter for that specific location from the various fixtures/adapters for that specific component.